Cefotaxime has a good meningeal diffusion and is effective at low concentrations on many bacteria, especially ampicillin resistant Enterobacteriaceae and Hemophilus influenzae. We have therefore used cefotaxime (150 mg/kg/24 h, continuous infusions lasting 30 minutes q. 6 h.) in meningitis due to gram negative bacilli. Twenty eight infants and children have been treated within 4 years. The 13 Hemophilus influenzae meningitis (including 2 beta-lactamase producers) have been cured without immediate sequelae. The duration of treatment could be reduced from 3 weeks to 2 weeks. The 7 infants with Enterobacteria meningitis (6 E. coli and 1 Serratia) have been cured of their infection with a 21 to 28 days treatment. The C.S.F. was sterile 2-3 days after treatment except a case of E. coli persisting during 7 days in C.S.F. contrasting with a normal ventricular fluid. A case of relapse with E. coli remaining sensitive was cured with a new course of the same treatment. Five meningitis complicated with hydrocephalus needed external drainage: the fluid was sterile 1 day after treatment in 4 of them. Two superinfections of ventriculo-peritoneal shunt due to Enterobacteriaceae have been cured. To obtain a good result, the need for a careful drug monitoring must be emphasized.